1. Field of the Invention
This invention relates to a differential pressure female mold having a replaceable mold insert therein for use in making short runs of thermoplastic articles which are custom decorated for private events such as birthday parties, weddings and graduations. More particularly this invention relates to a differential pressure female mold including a one piece, ring-shaped, decorating insert which is detachably received in a mold cavity for decorating a portion of the article being formed and a threaded retaining ring for securing the decorating insert.
2. Description of the Prior Art and Objects
Thermoplastic articles have been differentially pressure formed heretofore via differential pressure mold apparatus such as that disclosed in U.S. Pat. No. 4,969,812 granted to Gaylord Brown on Nov. 13, 1990. Such articles are frequently decorated with words, symbols or logos integrally molded, in the side wall thereof. The interior wall surfaces of the molds are formed with appropriate recesses and/or projections thereon to appropriately relieve the surface of the article being formed with the desired word, symbol or logo.
Such ornamentalizing is normally generic in nature and not personalized. Because of the relatively high cost of a mold, the cost of personalizing articles, such as cups for weddings, showers, birthday parties, etc., is generally prohibitive. Accordingly, it is an object of the present invention to provide differential pressure forming apparatus which will economically allow short runs of personalized thermoplastic articles to be formed.
It has been found that by placing a removeable mold insert in a female mold cavity, a personalized short run article can be manufactured.
The U.S. Pat. No. 490,966 issued to J. S. Irwin on Jan. 31, 1893, discloses a mold having a removeable die for forming an inscription in a glass jar being molded. With such dies, however, the article formed is sometimes aesthetically unacceptable.
The U.S. Pat. No. 3,380,121 issued to R. M. Chittenden, et al on Apr. 30, 1968 discloses a replaceable mold insert with indicia thereon, however, this patentee utilizes a multi-section mold with multi-section inserts in a blow molding operation. Other patents which were uncovered during a preliminary patentability search are as follows:
______________________________________ 4,979,720 Robinson Dec. 25, 1990 4,384,702 Boskovic May 24, 1983 3,734,448 Rusk et al May 22, 1973 2,919,470 Deters Jan. 5, 1960 2,054,553 Ballard Sep. 15, 1936 1,844,987 Slick Feb. 16, 1932 ______________________________________
Another object of the present invention is to provide differential pressure mold apparatus of the type described which can relatively and inexpensively mold personalized articles in a thermoplastic material.
It is another object of the present invention to provide mold apparatus of the type described which includes a ring shaped decortaing insert detachably received by a female mold cavity.
Yet another object of the present invention is to provide differential pressure mold apparatus of the type described including a mold body having a cavity which receives a ring shaped replaceable insert for ornamentalizing an article to be formed and a retaining ring threadedly received on the mold body for securing the insert.
A further object of the present invention is to provide mold apparatus of the type described including a one piece, truncated come shaped decorating insert detachably mounted in a female mold cavity.
A still further object of the present invention is to provide apparatus for differentially pressure forming an article in a sheet of thermoplastic material including a mold cavity and a detachable relief forming insert in a female mold cavity formed from a crescent shaped sheet of material having opposite ends rolled into a truncated cone with the opposite ends thereof in abutting relation.
Another object of the present invention is to provide an ornamentalizing insert for a differential pressure forming machine of the type described including a one-piece mold liner which has a hollow, truncated cone shape and is provided with an internal surface formed in relief to shape the contour of a portion of an article being formed.
Other objects and advantages of the present invention will become apparent to those of ordinary skill in the art as the description thereof proceeds.